Experimental evidence for narrow baryons in the mass range 1.0$\le$ M $\le$1.46 GeV

Abstract

The reaction p p $\to$ p ${\pi^+}X$ was studied at different incident energies around T$_{p}$=2 GeV. Narrow baryonic structures were observed in the missing mass M$_{X}$ and in the invariant mass M$_{p\pi^{+}}$. The masses of these structures are: 1004, 1044, 1094, 1136, 1173, 1249, 1277, and 1384 MeV (and possibly 1339 MeV). Some of them were also observed at the same masses in the missing mass spectra of the d p $\to$ p p X reaction although with a weaker signature. Many checks were performed to make sure that these structures were not produced by experimental artifacts. Several narrow small amplitude peaks, were also extracted using already published photo-nucleon cross sections. The small widths of all these results, and the stability of the observed structures, regardless of the experiment, were used to conclude that they are genuine baryons which and not merely the consequence of dynamical rescatterings. These baryons cannot be associated with classical $q^{3}$ quark configurations. We associate them with two colored cluster quark configurations.